1. Field of the Invention
The present invention relates to antenna test and measurement systems and particularly to a method and apparatus for establishing a threshold for acceptable phased array antenna performance which is dependent upon the number, size and location of failed components.
2. Description of the Prior Art
Present apparatus for testing phased array antennas include a beam steering computer unit and built-in test equipment. A typical phased array antenna includes a plurality of bays with subarrays including dipoles arranged in linear horizontal and vertical matrices incorporated in a planar dielectric radome, such as shown and described in U.S. Pat. No. 4,468,669. The beam steering unit controls a plurality of drivers which apply bias to phase shifter scanning elements connected to the dipole array to test and analyze various output parameters and faults. These include phase shifter bit-to-bit failure and various performance characteristics which are tested without causing degradation of antenna performance. Thresholds have been established to determine minimum standards of performance and maximum fault counts at which the antennas are rejected as unacceptable. The total fault count of the formerly used procedure, however, was arrived at without regard to location of the failed bits, made no distinction between large and small main array bits, and employed an incorrect heavier weighting of subarray bits as compared to main array bits. This resulted in a fault count which did not provide a sufficiently accurate basis for antenna performance projections.